Apparatus for the stabilization, rectification, and fractional distillation of natural gasoline



ay 1931- v F. s. WOlDlCH ,58

APPARATUS FOR THE STABILIZATION, RECTIFICATION, AND FRACTIONALDISTILLATION OF NATURAL GASOLINE Filed Nov. 6, 1924 eZ/i Iennop 775, [40/01 0/1,

wasted and subsequent losses of natural gasoline are the result.

The tailgas composed mostly of propane and butane is, however, a veryvaluable gas, because of its high calorific and illuminating value, andshould be extracted and recovered in a concentrated form for industrialand domestic purposes in line with the policy of this country forconservation of its natural resources. 7 I

. To evaluate this gas, we considercompari- 'son with methane or naturalgas, viz;

Methane has an average heating value of 1000 B. t. u. and anilluminating value of 5 British candle powers (B. C. P.), whereaspropane has 2650 B. t. u. and 35 B. C. P., and butane a heating value of3450 B. t. u. and an illuminating power of 54 B. C. P.

It is obvious from this comparison that this gas should be economicallyextracted from the natural gas with the natural gasoline in its entiretyand then separated from thenatural gasoline and liquefied and stored inhigh pressure steel bottles for the use of r the welding industry andfor domestic purposes, and thus be made a valuable source of income forthe gasoline industry.

In my process I shall describe a method of extraction of this gas fromthe natural gasoline, concomitant with the process of stabilizing thesegasolines and manufacturing special gasoline at thesame time throughfractional rectification.

Commercial cymogene is mainly butane which boils at a temperature of 34degrees F. and exerts a pressure of 15 lbs. vapor tension. 7

Despite this low temperature and high Vapor tension, natural gasolinecan hold safely a considerable amount of butane, without undue losses,particularly so if the propanes have been removed, and by a process ofsubstitution butane has taken the place of the propanes.

But there is nevertheless a surplus of butane which certain naturalgasoline cannot or 30 pounds.

hold safely beyond the law of intermolecular saturation, and itis thisbutane which we have to consider for conservation, either through amethod of blending to be explained later, or by recovery in liquid form,as cymogene, etc. 7

The temperature of the saturated vapor of propane is 49 degrees F.,exerting a tenl sion of 15 pounds and the vapors of propane would exerta vapor tension of 7 5 lbs. at 32 degrees F. at 60 Fahrenheit or 155 C.,the pressure required to condensebutane from its saturated vapors is 2atmospheres To condense propane'at 60 F. a pressure of 112.5. pounds isrequired.

Natural gasolines comprise a series. of hydrocarbons of various percentaes according to the source of the gases from which they were extracted.

In order to describe the process in question, a typical gasoline plantis assumed, which uses a combination compression and absorption processfor the extraction of nattural gasoline from the natural gas.

The gas is at firstsubjected to a pres sure of to 'lbs. and subsequentlycooled to about 60 degrees F. in order to remove the heat of compressionand to liquefy those constituents of natural gas which will have at thepressure and this temperature their dew point of condensation.

The gasoline so obtained will consist of the highest boiling pointhydrocarbons as decane (334 degrees F,), nonane (298 degrees F.), octane(257 degrees F.), heptane (208 degrees F.), and a small percentage ofhexanes (158 degrees F.) and pentanes (100 degrees F.). The percentageof recovery of the total gasoline yield from that gas may be assumed tobe 20%. This gasoline contains various amounts of dissolved butane,propane, and even natural gas, but will appear less wild, when exposedto atmospheric temperature and pressure, due to the greaterintermolecular attraction exerted by the higher boiling and molecularlymore complex hydrocarbons.

The cooled gas, deprived of its heaviest fraction of natural gasoline,now proceeds to the absorbing towers, where it will be deprived of itsremaining part of natural gasoline, through the medium of oilabsorption, the absorbing oil being deprived of its gasoline contentthrough steam distillation, whereupon it resumes its cycle of absorptionafter proper cooling of the oil.

The absorption process is carried out under the same pressure of 50 lbs.This compression and absorption tends to remove the highest and leastvolatile hydrocarbon from gas leaving the lowest boiling and mostvolatile in the gas.

The steam distillation of the absorbing oil should now yield theremaining part of thetotal natural gasoline yield, that is, 80%. Thefact, however, is that the steam distiliation yields only additional 20to 25% of the total yield, whereas the remainder of the gasolinerecovered will evaporate and go off as still-tail-gas when exposed tonear atmospheric pressure and temperature.

Since this tailgas carries off valuable higher boiling pointhydrocarbons from the residue gasoline, which would be lost, it istherefore subjected to a pressure of from 75 to 100 lbs. andsubsequently cooled, and by this third'cycle of manufacture theremainder of the total gasoline yield is obtained, amounting to from toof the total yield.

This last gasoline contains as boiling points at atmospheric pressuremostly pentane (100. degrees F.), butane (34 degrees F.), and aconsiderable partof intersolved cycle of manufacture. can take tom ofthe weathering deph'legmator "or evaporator WD.

propane (49 degrees F.), and'ethane, etc., which latter gaseousconstituents render all of the. recovered gasoline, when finally mixed,highly unstable, and unfit for most industrial purposes, and entaildanger in handling and shlpplng, not to speak of the lossesof-handling,.'when it once has left. the

premises of they plant; because aslong as it.

can :be manufactured in a'continuous and concomitant cycle with theprimary cycle of manufacture, and" the valuable foreshots,

such as propane and butane be recovered in liquid form as a commercialproduct, in-

stead of being wasted and being a continuous source of loss and trouble.i

In the accompanying drawing A1,.A2, and A3 are the receiving receptaclesor accumulators of the various gasoline products'as recovered under thebefore mentioned processes of extraction by compress1on,,absorption andreconipression of the residue tail gases from the steam still. i r

A2 receives the gasoline from the compression process at 50 lbs.pressure. Al receives the gasoline from the steam, still underapproximately lbs. pressure, and

A3 receives the gasoline from the recon pressor at approximately 100lbs.-pressure; 1 As fast these gasolines fall on from the respectivecycles of manufacture, they are at once removed through. :the automatic7 motor valves m1, m2 and. m3, andpipe lines 1,2, and 3.0verr1controlvalves '01, v2, v3 to a mixing header-1Z2, 3., and lto the hot.-

The mixing header 1, 2, 3, 4 is based on theinjector principle to insurethorough and intimate mixing of the various gasolines.

The gasoline with the highest pressure of 100 lbs. in -A3 exerts by itsexpansion through the release bym3a sucking action on pipeline 2 at 2,lifting the gasoline released through m2 from A2'under lbs.

pressure and increasesthe expansion capaci ity of the latter gas line,thereby mixing thoroughly between 2 and V The combined expansionofgasoline from A3 and AQ exertsa gain a suction on pipeline 1, llftingthe gasoline released through mi from Al,

increasing thereby its expansion, and

the 'uncondensable gaseous thorough and intimate mixingisfinallyeffected of all three gasolines in pipe-4,'lead ing to the bottomOfQdephIegmatOrWD;

' The weathering dephlegmator is built like a tubularcondenser as shown,consisting of a shell, two tubular plates-5 and 6 in which tubes t arerolled and expanded. Bafile plates 6 intersect the space between theshell and the tubes to..compelj the fiuidto flow around the tubes toacircuitous route insuring rapid circulationand intimate contact betweenthe cooling medium around the tubes andthe heating medium inside of thetubes.

In the following description the operation of the process and apparatusfor the stabilization of natural gasoline. proper will, be pointed out;that is, the natural gasoline as a whole will be simply deprived of thegaseous constituents and thenatural gasoline as a whole will beextracted with all its.

constitutents inherent to natural. gasoline,

which will be termed stabilized gasoline;-

To be more specific, we might term algasoline as. a stabilized gasoline,which yields with the standard A. P. I. distillationtest a recovery of98%, regardless, of the gravity.

of thegasoline, whereas unstabilized natural gasoline has a recoveryyield of from 90% to 95% only.

When the natural gasoline .storediin A1, A2, A3 under the respectivepressure. of

manufacture are released to near atmospheric pressure, an expansion-willtake place as above me'ntioned, and a cooling effect will be establishedby the expanding liquid andgases, andjthis cooling effect is made useof, to produce the necessary" dephlegmating reflux condensatlon from therising gasoline vapors and gases from the rectifying column or tower RT,to perform the function of fractional distillation and rectification ofthe complex natural gasoline hydrocarbon mixture, which it ,is proposedto free of its most volatile and gaseous constltuents. p

1 lhe action 'ofrefrigeratlon is carried out in parallel current, thatis the hottest vapors passing inside the tubular flues (t) upwards in"the weathering dephlegmator (VVD) ,are

subjected to a sudden'chilling action by, the

expanded natural gasoline and gases,enter-..

ing at the bottom of VVD and circulating around and outside ofthetubular fines; (2),)

and around t-he-bafflesn(b) rise in parallel current with the hotvaporsinside of the It 'isthis sudden chilling efiect on the hot risingvapors inside of the tubes which pro-.

duces a successful check on the-vaporizable constituents of gasolinethus. insuringintimacy of contact betweencondensable and which pass onupwards. I I I v The expanded natural gasolines, while 1 constituents,

passing around the flues in dephlegmator VVD, will absorb heat from thehot vapors rising in the hues and will be subjected to evaporation,driving out of the liquid gasoline all gaseous constituents as butanes,propanes, etc., which will, of course, carry with. them proportionalparts of vapors of the higher boiling hydrocarbons according to thepercentages present and their vapor tension exerted at that. temperatureand pressure under which the vaporation was carried out.

The vaporized gasoline, gaseous constituents and liquid gasoline leavethe dephlegmator VVD at the top through connection 19 and enter into aseparator 20, where the gaseous constituents and vapors are separatedfrom the liquid gasoline.

The gases and vapors leave at the top of separator 20 through pipeline21 and being a complex mixture of gases and valuable gasolinehydrocarbons, are now to be sub jected to rectification in tower RTwhich may be of any suitable construct-ion, though a rectifier of thecontact type is preferred, intersected in various places by selectivesealplates, insuring maximum deflection and contact between the vaporand liquid phase rectifying media- The gases and vapors are thusconductedto thebase of tower RT through pipe 21, but before entering thebase of tower RT, they pass through a mixing head 33, built after theinjector type, the purpose of which i is to first heat these relativelycool vapors and gases before they enter the tower, and

the second purpose is to thoroughly mix these gases and vapors with therectifying vapors coming from the thermo-srphonheater TSH through line31.

The gases and vapors coming through pipe 21 Wlll exert an llljGCfOleffect 111ml lng head 33, sucking off the hot vapors through line 31from the heater TSH, and.- will: be thoroughly co-mingled in pipe 34:

leading to the base of tower RT, passing upwards through the tower to besub ected to progress1ve rectifying action in counterfiow to therectifying reflux from the dephlegj mater and evaporator VB and theliquid natural'gasoline feed provided by separator 20' and pipelines 22and 23, controlled by valve 23. i

The liquid gasoline leaving separator 2 A at the bottom through. pipe 22is brought down to a convenient height from the service floor andconnected to a header h whence The exact location of this gasoline feedis determined by the nature of the gasoline be stabilized orrectifiedand can be calculated from the percentage composition of same: and thefactor of concentration.

The feed through line 23 will be considered at the present time only forthe desired stabilization of the total gasoline output.

The gasoline from line 23 finely distributed over the cross-section ofthe tower or fed on a selective rectifying plate flows down over thetower in counterflow with the rectifying vaporphase medium rising fromthe tower base and will be subjected to rectification throughprogressive evaporation and. fractional condensation of both media,establishing balanced rectifying levels of liquid and vapor phase, alllighter or volatile constituents establishing their levels towards thetop of the rectifier and all heavier or less volatile constituentsseeking their respective levels towards the bottom of the tower.

The gasoline thus flowing down over the tower will be progressivelydeprived of its gaseous constituents and most volatile hydrocarbons,whereas the uprising vapors and weathered gases from dephlegmator VDwill be deprived from level to level of tower RT of its less volatile orheavier constituents until they enterthe dephlegmator lVD to besubjected to refrigeration, dropping again the less volatileconstituents by condensation, which will resume its downward rectifyingcycle.

The gasoline having reached on its downward way over the tower the lastplate 25 of a selective type is drained from the seal of that platethrough pipe 26 to the base of the tower where a circular liquid seal isestablished between the tower shell and a cylindrical extractionreceiver 27, pipe 26 being sealed against passage of vapors intothis'seal.

From this seal the gasoline siphons down through line 28 to the bottomof the thermosiphon-heater TSH consisting as shown of a shell with twotubular fiueplates in which the heating tubes t2 are expanded and thespace between the shell and the lines being so constructed as to compelthe gasoline to be heated in a circuitous route.

In this heater the gasoline will be subjected to steam heating, causingpart of the gasoline to evaporate. This is done through live steam,admitted to the top of the heater through control valve 36 and line 36,passing inside of the tubes of the heater in counterflow to the gasolinecirculating outside of the heating tubes.

The evaooration of part of the gasoline in TS I will set up a rapidcirculation of gasoline from the tower base through the heater and backto the tower base, due to the thermo-siphonic principle involved and onaccount of the injector effect established inthe mixing head 33 asalready mentioned.

Here a thorough treatment is imparted to the gasoline before it isextracted as stabilized gasoline' because in. therapid circulation'fduringtlie heating;treatmenhrall intersolved gases r are 'finally,driven; out and join their way with the "gasoline'vapors upwardsthrough-the tower. The gasoline freed of all gaseous constituents,however,

is siphoned back into .the'extracting receptacle 27 through coniiection32,from"where it will flow: as a finished;product.:thrbugh line 35 to.the stabilized gasoline eoolerSt GG, where .it willbe cooled by flowingin-- sideof coil C l-incounter flow to the cooling water, enteringthroughlwl and leaving through @112, whereas the gasoline will leavethroughisight box 1 line 36a to receiver 0i accumulator A L-land throughmotor valve m and' line a l to betra1 1sferred to the storage tank; a lr The-action of the 'thermo-siphon-heater and its liftingepower fromalowerlevel to, a-higherlevel of the liquidinvolved, is based onparallel current circulationof liquid and its heat generated vapors,Ithe bouyanoy of the la tter inducing a rapid circulation, due toexpansion from liquid to vapor-phase has not reached the temperature ofevaporation of these rconstituents.

These evaporators arej therefore exceed- 'ingly sensitive, quiekinaction and capable ofioverloadl and very economic." This evaporator is avery important part ofthe rectifier, due to its gas-expelling,eliminating and separating action, i'.. e.',that no gas can passed theevaporator, and the 1 gasoline lifted back to receiver 27 is thereforefree of all'intermolecular dissolved gases, in conj trasdistinctiontoirectifiers using heaters of i 40 the common type, as acoil' inastill, or tulifted withthe rising 'vaporsiand gases in 31, and isdischargedthroughline ,32 into ireceivel 27, whereas, the vapors and?gases are suckedpff in by-theifirst gas phase' of VYD, and enters RTthrough 34:. .7 Atthe point whereline 32 branches off line 31., a liquidseparator is "provided, which is'not to effect a clean separation ofvapors and gases from the residualliquid, that is the H polnt ofntermolecular saturation andan rectified gasoline. The .siphonic actionto lift the gasoline back to the t'ower base is caused through the abovebuoyancy'of gen- VI erated vapors in parallel. cycle, and the pri-' marycausezof this lift is, of course,-due to heating, therefor, the name:thermo-siphone heater. Y

a 652 Gontrolvalve 36 for live steam is conand causingalso theevaporation of lower boiling fractions, though the temperature thegaseous constituents are separated from, the liquid, the first leaving.through line 12.

and the latter through line l3, which leads: to a header hl, where the.condensedliquid actuallyT stay in the gasoline after it has:

through line 12 consistmostly of propane and butane with traces ofethaneand methane.

shown, being only a diagrammatic sketch,

uents, which resume the cycle of reflux down 7 over thetower. The gasesand remainingvapors thus-leavingthe'tubes t in dephleg-" mator WD arenow leaving at the top through: pipe 8 andenter the top oflrefrige,crating dephlegmator RD, downwards" through the fines t1 in counterfiowtofthe refrigerating medium entering throughiline 47 at the base of RDandfcirculating around:

' the tubular fines and the circulatingbaflies 51, Here as We will pointoutlater on,. an

; intensified cooling action is effected on the gases and.vaporsiand-the remainder of cone densable' hydrocarbon constituents willa have been liquefied which. will collect on the bottom of thedephlegmator. plate? 7 and finally 1 leave with the gases at the bottomdephle'g- Inator RD and enter the separator 11, where Ican'bisdistributed throughflines 14,115, 16, r 17, and 118,. accordingto. the requirements, controlled by the valves 14, 15,16, and

In my present case, referring toistabilization proper, the condensate isdischarged throughline let into the'top of thetower RT to perform hereits function of rectify-s ling reflux 'over the tower, that lSl formaximum concentratlon. V V i The remnant gases leaving separator 11 IProvided that the substitution of i the propanesfor' the butanes in thenatural gasolinefcould have been effected in the rec- 1' 11'5" ratherintermolecular saturation and if no i surplus 'of butane availablebeyond that 1 point, the gases in question will mostly con- 'sist ofpropane and small. percentages of l 120 tifying' tower to the? point ofmolee'ularcor ethane andjmethane; V u a 1 But actual experience andpractice shows; thatbutanes always exceed in quantity the remnant gasesfrom the stabilization process 113 0 through hotvblending with-a refinednaph pass from line l2, entering at the top of the tower and pass inparallel flow with hot naphtha vapors or with hot finely atomized liquidnaphtha through a proper contact material (F), filling the tower BT andleaving the bottom of the tower through line 3S'to blended gasolinecooler BGC, where gases and naphtha will be cooled in coil 02, passthrough sight box lgto accumulator A5 for blended gasoline, where itwill be released through motor valve m5 and line to the storage tank.

The remnant gas, consisting mainly of propane, will accumulate andsettle out at the top of accumulator A5, where it will be retained toset up a small counter pressure in the stabilizing system and thesurplus of gas will find exit through the relief valve RV and beconducted through line 42 over a storage tank, not shown, to the suctionend of compressor C through line 44.

Here these remnant gases will be subjected to pressure of liquefaction,ranging approximately from 400 to 450 lbs, depending on the compositionof the gas as pointed out on pages 3 and 4 of this description.

The compressed gas leaves the compressor through line 45 and passesthrough water cooling coil C4 of tailgas-cooler TGC and leaves thecooler through 46 to accumulator A7 where the liquefied propane, orpropane and butane of my later description will be stored. The remnantgases left as ethane and methane will be retained to setup the requiredpressure on gauge P2 and the excess of these gases will find exitthrough relief valve RVl and line 51, being returned to the natural gassupply of the plant.

When enough liquid propane, 0r propane and butane has been accumulatedin accu mulator A7, the refrigeration cycle for the refrigerationdephlegmator RD is set in operation.

Expansion valve 47 is carefully cracked and exit is given to the liquidpropane, leavingthrough line 47 and entering at the bottom ofdephlegmator RD and expanding from about 400 lbs. pressure to thepressure established in the stabilizing system and controlled bypressure gauge P1 on accumulator A5, thereby causing an intense actionof refrigeration around the tubular flues t1 of dephlegmator RD andabsorbing the heat from the hot gases inside the flues, evaporation ofthe butane-propane liquid will set in, as far as the liquid has notalready vaporized through the expansion.

The gases leave the dephlegmatorthrough pipe 48 into separator 49,where, eventually, escaped heavier hydrocarbons, as butane and pentanemay be re-cycled in liquid form back to the stabilizing system, leavingseparator 49 at the bottom through line 50 and feeding over a siphonseal to reflux line 13 and through line 14 back into tower RT.

The expanded gases leave separator 49 at the top through line 44,resuming theircycle back to the suction line'ofthe compressor C to behere reliquefied and to resume its cooling cycle anew through expansionvalve 47' and line 47 to dephlegmator RD.

The quantity of liquid propane or propane and butane, as the mode ofmanufacture may require, to be kept in the refrigerating cycle to effectthe required cooling effect in dephlegmator RD can be determined andcontrolled either through an orifice meter ahead of expansion valve 47or by an automatic control through the interaction of thermostat T2 inseparator 49, or T1 in separator 11 and the expansion valve 47 proper.

In the course of continued operation of the process an excess amount ofliquefied propane and butane will be produced over the cyclerequirements for refrigeration, which excess can be withdrawn from theaccumulator,through line (L7 to a pressure storage, where the liquefiedgases can be withdrawn in. steel bottles and sold for industrial weldingpurposes or for domestic heating and illumination, etc.

In describing the stabilization of natural gasoline proper, we have seenthat three products have been produced: (1) stabilized gasoline from thebottom of tower RT; (2) blended gasoline, and (3) liquid propane, orpropane and butane, as commercial cymogene.

Going back to the manufacture of blended gasoline by means of a refinednaphtha from the distillation of crude oil, we have pointed out that theexcess butane over the point of intermolecular saturation of naturalgasoline may be recovered in blending tower BT. However, the blending ofbutane with naphtha Would not render a satisfactory motor gasoline dueto the gap of missing hydrocarbon series between the hutane and the nextlowest boiling hydrocarbon of the naphtha, which would be hepta-ne andoctane.

To flll this gap and have a satisfactorily blended gasoline an adequateproportion of pentanes and hexane has to be provided in the cycle'ofthis blending operation.

Looking at the drawing we see line 16 branching off from header 7L1 forthe distribution of the reflux of dephlegmator RD through line 13 ondover line 14 and control valve 14 to the top of tower RT. If valve 16 isopened in line 16, we see that a part of this reflux can be withdrawnthrough line 17 to the top of blending tower RT; or if valve 18' isopened in line 18, an adequate amount of reflux can be withdrawndirectly in the cooling coil C2 and thus the missing hydrocarbons can beadded through the proper conduct of operation of dephlegmators WD andRD.

The hot blending can be carried out as vapor blending, or as hotblending in liquid phase.

ing pump NP takes naphtha front storage tank NT through l1ne51 anddischarges terfiow to the heating medium, steam, out-. side of theflues, SllPPllGCl' by line 58, con trol valve 58, valve 57 and line 57.A et of direct: steam may be supplied through control valve 59 and line591110 the naphtha feed line 54, if necessary. I

-The.water of condensation from the heater NH is withdrawn through andwater trap TR to be returned to the boilers. The

same pertains to :the thermo-siphon-heater Trlandreturned to theboilers.

37', 37", 37" are sample cocks *forthe inspection of; the products run.

Having described the operation ofstabilization of natural gasolineproper, that is to remove-from the natural gasoline complex all gaseousconstituents and have two dis tinct products, namely, stabilizedgasoline; (and liquefied propane and butane, the blending operationbeing herefofaninordmportance, due to the drynessloflthe. remnantgases,we nowprioceedand describe its second operation, where the naturalgasoline icomplcX ,may be-subdividedi in any'desirablecuts or fractionsof special specification, such as solvent gasolines'for the rubberindustry, special gasolines for the varnish in--' dustry ordry-cleaning, etc, where the inig boiling point range which may be thoseor the lighter constituents or those of the heart fractions, or those ofthe tail fractions.

Here the blending operation .will be of great importanceto make useof'all lighter constituents by bindingithem to refined naphtha andproduce a' uniform andstable motor gasoline, which will havethegsamecharacterlstlcs as a good straight run" gasoline, andthen to have atailgas which will be richer in butane and therefore produce a producttermed commercially as cymogen. The operation of fractional distillationof natural gasoline in this instance will becar ried out athighertemperatures at thermometers T*at .the towerbase anduTL at the towertop, therefore more lighterFconst-itu cuts as butane, pentane, andhexane will leave the tower top and besubjected.tohot naphtha blending,resulting in astable m0 1 tor gasoline. j'

.The gasoline extracted at the tower base;

willtherefore contain less volatilefconstit- .uents and be almost asstableasan average In the drawing,v is shown vapor, phase blending ofnaphtha.- .Naphtha blend-V saturation. 5

. A2,,A3 willjbejfecl as fast as they are manufactured hr the,beforadescribed way through lines .1, 2, 3 to the dephlegmator VVD' andherebe subjected to evaporation or I weathering, exerting at the sametime a refrlgeration effect on the vapor-gas mixture emergingfrom the:top of the rectifier and produced through the thermo-siphonheater, TSHat the base of' the tower RT. The; weathered, gases and vapors of thenatural gasoline complex are, entering the 'tower base ofRT through line21 from" liTSH, where thewater of condensation is Withdrawn through line37 and steanitrap' t separator 20, over the .mixing head 33 andconnection 3 f,- properly preheated and mixed with the rectifying vaporsemerging from heater ,TSH: through line 31. v

The heated vapors iandf gases rising through tower RT upwards in counterflow. to the reflux from WD and, RD and the gasoline feed from line 22over valve 23 and line 23, will cause" from plate to plateor level tolevel fractional distillation of re-r flux: and gasoline feed and be inreturn I ing the substitution ofpr'opane for. butane tial boiling pointof these gasolines and their endpoint lay close together and covering ain the liquid phase of the downflowing gasoline, etc., to the Thegasoline feed will now be changedfrom line 23-150 line 24,;controlled byvalve 24', that is close to the tower'base. The reason for this changeis to effect in the tower above feed line 24 concentration of and toestablish on the various selective plates the [concentration ofhydrocarbons point of intermolecular 11 0b I i with close boilingpoints, from wherethey can vbe extracted continuously according to thespecifications desired as shown. by ezrtracting lines a and .62,controlled by valves 6 and 62, either single or COmblllBCl, or 1n anyother multiple form or their. combination's, and are extracted,through-a header over valve. 61 and line 63 to specialgasoline" l cooler,SGC passing through coil "C3 in cou'nterflow to cooling water from1/15, oyer look-box 1 to accumulator A6 and from hereover m6 and a6tothe storage tank.

' The reason for the change of level from a 23 to 24 is,'th at the feedof unstabilized" gasoline must be below the two extraction lines 6 and02 with valves 01 and 02, because otherwise unstable gasoline would beextracted through these intermediary ex- The extracting lines 6, 02,etc, with their valves 0, 62, etc, can be brought down to the servicefloor for easy handling by the operator and small test coolers will beprovided where the gasolines to be extracted can be inspected andtested, after balanced conditions are established in the tower RT.

According to the level or selective plate where the gasolines arewithdrawn, the quality of the gasoline will always be the same and theircombinations will render any gas 'oline desired of any specification,without changing the mode of operation of the process or tower. Thesegasoline fractions can embrace the lighter hydrocarbons at, the top ofthe tower, or the heart fractions as shown by 61 and 62 and anycombinations thereof.

Without any additional operation expenses for labor or fuel, etc., thesespecial gasolines can be manufactured at a moinents notice and tosatisfy the demands of any special markets and reap the benefit of theconcomitant better and higher prices.

It is well understood that the extraction of this gasoline from thevarious selective plates is only partial without interfering with theoperation of the tower RT in those parts which lay below these selectiveplates.

The gasoline extracted from the tower base through line 35 fromextraction receiver 27 will embrace the most stable gasolinehydrocarbons and contain the lightest constituents only in smallfractions rendering a splendid gasoline as solvents for the rubberindustry, etc., or making a No. 1 aviation gasoline.

If this gasoline should need any adjust-- ment as to its initial boilingpoint or to straighten out the characteristics of its boiling pointcurve, this can be easily done by "supplying any of the desiredconstituents through feed valve 62 and feed line 62, which is the linebranching off of 35 with valve 62 joining into the header with th line03 and valve 61.

The vapors and gases emerging from dephlegmator VD after being subjectedto the first refrigeration through the expan sion of the naturalgasoline feed 1, 2, 3, leave through line 8 and pass in counter currentflow the tubes $1 of final refrigerator and dephlegmator RD to yield inthis refrigeration the second supply of rectifying reflux, rendering theremaining gases more or less dry, according to desire, depending on thetemperature maintained at the exit of this dephlegmator at thermometerT1 in separator 11.

Due to the desired higher concentration of the gasoline hydrocarbons inthe upper part of the tower RT, maximum refrigeration and maximum refluxwill be required to accomplish that end, which means that a greateramount of liquefied propane and butane in A7 will be kept in therefrigeration cycle. 1

But inasmuch as I want to produce a blended motor gasoline throughnaphtha blending I am able to allow the passage of the required butane,pentane and hexane hydrocarbons and recover same in blending tower BT,or supply these constituents through feed line 16 or 18 from the refluxheader hl, or if I desire, I can recover them in the refrigeratingdephlegmator RD and at disposition for the maximum concentr tion in therectifier.

The gases and vapors leave separator 11 through line 12 and aresubjected here to the removal of all valuable gasoline constituentsthrough hot blending with naphtha as before described, being extractedthrough 88 and cooled in BGC by Water through 103 and accumulated in A5as finished product.

The remnant gases composed of propane and butane leave the accumulatorA5 through 41 and relief valve RV and pass through 42 and 12 to thesuction line 44 of compresser C, where they will be liquefied bypressure and water cooling, stored in accumulator A7 and resume here therefrigerating cycle through the dephlegmator RD and return fromseparator 49 through line 44 to the compressor, whereas the eventualliquid part of the condensation, consisting of higher boilinghydrocarbons, may be re turned through line 50 to the reflux produced inRD and extracted through line 13 to be returned to the tower RT throughline 15 controlled by valve 15, instead of through line 14- aspreviously described.

The reason for this is the same as previously pointed out for thegasoline feed, only the feed of the reflux will be carried as close thefeed lines for gasoline and the respective primary or secondaryrefiuxes, because they depend on the raw material to be rectified andthe products to be extracted, and it is an easy matter to subject theproper constructlon of a tower of this sort, serving certain conditions,to the necessary m'athematical calculations with regard to desiredconcentration and the physical analysis of theconstituents present inthe raw material-and thereby making proper. provisions for the enterinto practical deviations as far as they the operation of such aprocess.

operation of this process of fractional distillation and stabilization,we see that the gasoline complex as a raw material with gaseousconstituents intersolved, which render it unstable and unfit for manypurposes and causing great losses in handling, etc., can be subdividedby this process in groupconstituents of any desired combination orspecification and that all products contained in the raw naturalgasoline can befimade available and be recovered for certain purposesanduses.

a I have subdivided this complex natural raw gasoline first in theforeshots, the-remnant gases, propane and butane, in liquefied form as aby-product of this process, available for many uses, particularlyindustrial welding, which is an important feature in theoilfieldsy'second, a blended motor gasoline which solves the problem ofeconomically disposing and making use of theexcess amount of butaneswhich are present in all raw gasolines beyond the point ofintermolecular saturation; third, in the extraction of any gasoline of acertain specification for certain industries, the manufacture of whichentails difficult problems if their manufacture is detached and separatefrom the manprices.

ufacture of raw casinghead or natural gasoline, because of the necessityof special equipment as compressors, etc, and the power requirements forcheap and efficient extraction, which requirements are,,however, therule in any gasoline plant and do not require any material extra outlayof money; fourth, in a stable residue gasoline, which can be used as aspecial gasoline'for many: purposes as solvents, etc, or asanaviationfuel gasoline, commandingthe' highest This, however, is not all in myconsideration of the economic importance of such a process and apparatusas far as its stabilized and refined products are concerned and theirdisposal without undue lossesrand avoiding the factors of danger.

The most important feature relates to the possibility of stripping thegases from which the natural gasolines are, extracted of its totalamount of valuable gasoline hydrocarbons, which in the majority of allgasoline plants could not be accomplished, because of concomitantincreased recovery of gaseous hydrocarbons as propanes and butanes,whichhad to be continuously recycled, without getting rid of them in a drystate and without loss of the recovered gasoline constituents.

sources. V. i p .From this point ofview, it is believed, that near thebottom 'thereof for 'conducting c l ifiicultiestofythe concomitantincreased yield ofv :this propane and butane-gases and' as a i matteri'of. fact, "their 5 losses rather increased 7 gf-anddecreased'theirvaluableyields in-"natu- Resummg the conclusionsofthe results of K 1 i The installation, however, of a stabilizi-ng andrectifyingtower will ina'ke possible the maxirnumextraction of naturalgasoline from gas, as also the propane and butane hydrocarbons will :nowbe valuable products and will be disposed of and extractedas fastv-as'theyareproduced' for: the benefit oftlie plant owners," aswell asfor .thef-country, which has all reason 'tobefdeeply concerned with theconservation of the. natural rethe average yield of extractable naturalgas .oline; could be increasedriby a t least 10%,

Most oftheimanufacturers ofnatural gas- I -ioline abstained fromrecovering all available natural gasoline from the gas, 'becauseof theexclusive of the extra yield the valuable a concentrated form.

from .and tozthe bottomof said column,- a weathering dephlegmator'Ifixed to the 1 top of said column, means for conducting .gaso- :linesfrom the storage system into: said dephlegmator; to expand therein, said.dephlegmator including a plurality offiues forlcon ducting' gases andvapors from said column;v :2. Apparatus oft theipharacter described,

including a system for storing natural gasol1nes at different'pressures, a thermo siphon "heater, a rectifying column above saidheater, a mlxinghead connected to said column near the basetthereof,means including sald mixing head connectedxto saidwcolumn fiuidsjthrough saidiiheater afromand to the bottom of said column, anexpansion chamber closed to said column and connected to the topthereof; meansfor conducting gasolines from said system to the bottomof; said chamber to mix and expand therein,

fiues extending through said chamber to conduct gases and vaporsfromsaid column .to heat the expanded gasolines in said chamber, aseparator connected to the top of said chamber, a pipe connecting thetop of said separator to said mixing head, and valve controlled" pipingconnecting the bottom ofv said separator to saidcolumn at difierentheights therein,

3. The apparatus set forth in claim 2 in combination with arefrigerating chamber mounted on the top of said expansion chamber,means for conducting gases and vapors from said fiues, to the top ofsaid refrigerating chamber, a separator connected to the bottom of saidrefrigerating chamber, a naphtha blending tower, a pipe connecting thetop of said separator, to the top of said tower, means for heating andfeeding a fluid to the top of said blending tower, a storage tank, andvalve controlled fluid conducting and cooling means connecting thebottom of said blending tower to said storage tank.

4:- The apparatus set forth in claim 2, in combination with arefrigerating chamber mounted on said expansion chamber, means forconducting gases and vapors from said flues to the top of saidrefrigerating chamber, a separator connected to the bottom of saidrefrigerating chamber, a storage tank apparatus including aheater andblending tower connecting the top of the last named separator to saidstorage tank, valve controlled piping connecting the bottom of the lastnamed separator to said rectifying column at various heights therein andto the top of said tower.

5. The apparatus set forth in claim 2 in combination with arefrigerating chamber mounted on said expansion chamber, means forconducting gases and vapors from said fines to the top of saidrefrigerating chamber, a separator connected to the top of saidrefrigerating chamber, a storage tank, and means including a compressorfor connectingkthe top of said separator to said storage tan 6. Theapparatus set forth in claim 2, in combination with a refrigeratingchamber, mounted on said expansion chamber, means for conducting gasesand vapors from said flues to said refrigerating chamber, a separatorconnected to the top of said refrigcrating chamber, a storage tank,means including a compressor connecting the top of said separator tosaid tank, and a valve controlled line connecting said tank to saidrefrigerating chamber. i

In testimony whereof I afiix my signature.

FRANCIS S. WOIDIOH.

